FIG. 4.
Inhibition of Env binding to the viral receptor by 667. (A) Masking of the 667 epitope on cell-bound CasBrE Env. A total of 5 × 105 BALB/c cells were incubated with soluble Env from a supernatant cleared of virus corresponding to a titer of 5 × 104 FrCasE FFU. They were subsequently subjected to flow cytometry analysis with the r667, 83A25, and 709 MAbs as described in Materials and Methods. C, control cells. (B) Detection of Env on FrCasE-infected M. dunni cells by r667 or 709. A total of 105 control (C/709 and C/r667) or M. dunni cells infected with FrCasE as in panel A (IC/709 and IC/r667) were incubated with 5 μg of 709 or r667 MAb per ml, respectively, for flow cytometry analysis. (C) Binding of FrCasE Env to BALB/c cells in the presence of p667. Soluble Env obtained from a viral supernatant corresponding to 5 × 104 FrCasE FFU was incubated with 100 or 10 μg of p667/ml or with no MAb and added to 105 BALB/c cells for flow cytometry analysis with MAb 83A25 for detection. Noninfected BALB/c cells (C) were used as negative controls.